The present invention relates to the field of telephony announcement systems, and more particularly to a system allowing a telephony announcement platform to be shared between telephony switches.
The traditional approach to providing announcement functionality for a subscriber served by a central office switch is to equip an announcement platform co-located with the switch and connect the announcement platform to the switch with dedicated circuits. These announcement platforms provide information to callers, speaking announcements such as xe2x80x9cYou must first dial a one when calling this numberxe2x80x9d or xe2x80x9cThe number you have dialed has been changed. The new number is . . . xe2x80x9d A telephone network comprising two switches, communicating with each other over regular trunks, and each switch having a co-located announcement platform is shown in FIG. 1. Telephone instruments connected to a switch typically only access the announcement platform associated with that switch. There are several problems associated with the traditional approach to providing announcement functionality. Increasing the announcement capacity to multiple announcement platforms in multiple switching offices can be very expensive. It is also possible that in a multi-vendor environment, the needed announcement platform equipment to increase the capacity may only be available from the original vendor. Similarly, upgrading announcement platform functionality for multiple switching offices can be very expensive. Also, announcement system message maintenance requires that maintenance be performed on each announcement platform. This can be time consuming and may require specific expertise about several different types of equipment in a multi-vendor environment. There is also an inherent risk of failing to synchronize all of the announcement platforms, resulting in different subscriber treatment depending on which platform serves the subscriber.
Accordingly, there is a need to reduce the number of announcement platforms in a network, thereby easing the burden of maintaining a multi-switch environment.
One solution to this problem is to provide centralized announcement platforms in the network each serving a number of switches over dedicated trunks. FIG. 2 shows such a network comprising four switches, communicating with each other over regular trunks, and two centralized announcement platform Each centralized announcement platform is shared by two of the switches over dedicated trunks. As in the non-centralized platform environment, telephone instruments connected to a switch typically can only access the announcement platform associated with that switch.
This solution eases the platform maintenance burden by reducing the number of announcement platforms in the network. However, there also is a need to reduce the total number of dedicated circuits serving announcement platforms, and a need to provide redundancy such that, for example, in the case of an announcement system all circuits busy condition, an alternate designated platform can provide announcement services to the calling party.
The present invention provides a system in which centralized announcement platforms are connected to xe2x80x9chostxe2x80x9d switches over dedicated trunks. A remote switch needing announcement services sends a signaling message to a host switch requesting a connection to the announcement platform. A connection is then established between the host switch and the remote switch over a regular trunk, and the full connection is completed over one of the dedicated circuits between the host switch and the announcement platform. Announcement message ID and other information required by the announcement platform is coded in the available parameter fields of a signaling message.
In the present invention, the trunks that were present in the prior art between a remote switch and the main distribution frame at the office of a co-located centralized announcement platform have been converted to regular trunks between the remote switch and the host switch, and the trunks, that were present in the prior art between the distribution frame and the centralized announcement platform have been converted to dedicated circuits between the host switch and the announcement platform. With this arrangement, an economy of scale is realized. In the present invention, both the total number of circuits required between the remote switches and the host switch office, and the number of announcement circuits on the centralized announcement platform are less in number than the respective values of the prior art centralized system.
The invention also provides for redundancy in the event that announcement circuits on the centralized announcement platform are unavailable. If a request for a connection to the announcement platform is rejected by the host switch, the remote switch can send another announcement platform connection request to another host switch.